Pneumatic engine or tool.



J. D. MACDONALD.

PNBUMATIG ENGINE OR TOOL.

APPLICATION FILED JAN.13,1912.

Patented Sept. 8, 1914.

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IIIIII IIIll LII WITNESSES ma.

JOSEPH D. MACDONALD, OF BUTTE, MONTANA.

PNEUMATIC ENGINE OR TOOL.

Specification of Letters Patent.

Patented Sept. 8, 1914.

Application led January 13, 1912. Serial No. 671,049.

T0 all lidiom. it m c i/ concern Be it known that I, Josemi D. MAQDoN- `\Ln, a. citizen of the United States, residing at Butte, in the county of Silver Bow and State of Montana, have invented certain new and useful Improvements in Pneumatic Engines or Tools, of which the followingl 1s a specification.

My prsent invention pertains to an 1mproved pneumatic engine or tool, the construction and advantages of which will be hereinafter set forth, reference being had to the annexed drawings, wherein:

Figure l is a longitudinal sectional View, showing the parts in that position m which the live air is in the act of forcing the hammer forwardly or to the right to deliver a blo-w, the course of the air being shown by the arrows in full lines; Fig. 2 a similar View, the hammer being shown as actually delivering a blow or coming into contact with the drill-head or anvil, the course of the exhaust air being indicated by arrows in dotted lines; Fig..3 a longitudinal sectional view of the hammer proper; Fig. 4 a transverse sectional View of the structure taken upon the line Ll--l of Fig. l; Fig. 5 a longitudinal sectional view of the combined piston-hammer support or guide and abutment member against which the com* pressed air works, said member likewise forming the conduit through which the compressed air or other motive Huid is introduced; Fig. G a sectional perspective view of the various elements employed to secure the combined guide and abutment member in place within the shell or casing; and Fig.

7 a perspective view of the rear end of the hammer proper.

The main object of the present inventlon is to produce a simple and highly etlicient pneumatic tool which by reason of its construction is small in diameter and is free of valves except as the movable piston hammer itself performs the function of a valve, or a plurality of valves.

The tool or hammer is of the tandem type, and the compressed air is introduced centrally into the piston-hammer support and thence distributed through suitable ports so that it mav act equally upon all of the abutments or fixed faces to cause a forward inipulse or movement to be imparted to the hammer or movable piston. The ports are likewise so arranged that immediately the hammer has delivered caused the hammer exhausted and the its blow the air which to function will be freely 0 incoming compressed air will act to return the piston-hammer to its initial position. The force by which the hammer is returned to its initial position preparatory to delivering a second blow is .less than that which is employed in delivering the blow, and this reason of the fact that the air acts upon a less number of faces or abutments in the return stroke than it does in the outward or hammer stroke. the present instance two abut-ments or faces are exposed to the compressed air in making the outward stroke, While but one face is brought into use in making the return stroke. It is conceivable that a greater number o-f faces may be used, but in each instance the fixed abutments or faces employed in producing or effecting the hammer blow should be greater in number than those employed -in causing the return of the hammer to a position where the live air is again delivered; to the parts to effect the hammer blow.

Referring to the construction shown in Figs. l to 7 inclusive, l denotes` the shell or casing of the engine or hammer, having secured to its outer or forward end a suitable cutting too-l 2 provided with a stem or anvil portionv 3, secured in the shell by a cross-bar or pin 4. Said 'stemand tool are provided with suitable exhaust ports 5, 6 and 7, through which the exhaust of the tool may discharge directly into the h o-le being out. Thecutting tool herein .shown forms no part of the present invention, and any tool suitable for the work may be employed.

To the oppositeend of the shell there is secured in any suitable manner the usual feed bar 8, having a port or opening 9, through which live or compressed air or other fluid medium under pressure is introduced. Located within the rear end of the shell and permanently positioned therein is the combined piston-hammer support and abutment member, shown in sectional elevation in Fig. 5. It comprises two tubular stems or portions 10 and l1, open at their distant ends, tube l1 being considerably longer than the tube l0. The limit of the two tubular members is defined b v an intermediate abutment and piston-guiding niember 12, said member having an external dimembers and provided with einher Iii has termed erewith a collar la, and the 'Y r end of the stem or tube is threaded, as at l5. 'luc tubular member l0 is provided with a port it, and. member il with a port l?, said ports beingformed adjacent to the abutment l2. rllo secure said combined abut-- ment member and pistonehammer guide fizredly in place a ringl 18, packing 19, ternallygrooved ring 20, packing 2i. and nut 22 are employed. Said parts are slipped over the threaded end l5, and the members passed into the shell (this, ot course, before the engine is secured to the drill, or leed-bar 8 is secured in place, and after the hammer' piston is mounted on the abutment guide), after which a cross-pin is passed through the wall of the shell, said pin lying within the groove of the ring 20. `Upon then screwingI up the nut the paclrings are compressed and forced outwart'll into close contact with the inner wall ot t ie shell.

rllhe combined piston and hammer is shown in detail in Figs. 3 and 7. lt may be said to comprise a :forward tubular portion 2st, having a closed and relatively heavy hammer or head section 25, a rear tubular section 2G, somewhat larger in external diameter than the forward portion, and an intermediate piston or piston-ring 27, provided with a paclring 28. The bore 29 of the forward portion 2t is of a diameter to malte a close lit with the stem l0, and said bore merges by the inclined tace 30 into the somewhat larger bore 3l et section 26, the diameter of said. bore being such as to make a close lit with the abutment member l2. The rear end of section 26 is internally threaded and a shouldered sleeve 32 is screwed into the same, the bore et the sleeve making a. close working t with the outer face ot the tubular stem il when the parts are assembled.,

ll/lember is provided with ports 33 and 341-, adjacent to the piston member 2'?, and member 26 is likewise provided with ports 3.5 .and also adjacent to the piston. A, port 33'? likewise 'formed in member 26 to the rear oli the ci, iter thereof. Me lber 26 is likewise provided with external ribs 38, which make a close lit with the bore of the shell or casingy l., and acting` in conjunction with piston 2T, serve to guide and center the piston-hammer.

r lfhe'operation ot the structure is as 'ich lows, assuming, of course, that a constant supply oi' iluid under pressure is supplied through port 9: lli/lith the parts in the position shown in Fig. l, the air passes through' tube ll. which forms a support and guide 'for the collar or sleeve out port i7, into the space or chamber d hated by 39 hetween the portion. and tube ll, and between the abutment 12 and the inner end of sleeve 32; thence through port El?, into the space between the outer face olf member and the interior of the shell, passing rearwardly and forwardly; rearwardly past ribs 38, against the lixed collar lll, which may be termed a xed abutment, and forwardly through ports 3b and 1G into .the tubular stem and guide l0, which discharges into chamber 29 of the hammer. The compressed air acting between collar le and collar 32, and within the chamber or bore29, between the forward acethereo'f and the forward Y tace of abutment 12, tends to force the pis toirhammer forwardly toward the right and brings the hannner-head 25 into Contact with the anvil 3, the force of the blow im-` parted being dependent upon the air-pressurer ln Fig. 2 the parts are shown as just having functioned to deliver a blow and when in such position the exhaust ports are opened to relieve the pressure from between' the collars and from within the bore or chamber 29, the air eXh austin g as shown in dotted arrows. At such time, however, and

in order to retract the piston-hammer the compressed air still passes into chamber 39, which at such time is restricted in size and likewise closed, by reason of the fact that port 37 is carried 'forward beyond the solid abutment guide 12. rllhe- `compressedV air will, by reason of its expansion in the chamber, 'acting against the fixed abutment l2 and the collar 32, 'force the pistondiammer rearwardly or to the lett, and such motion will continue until the parts resume the position shown in Fig. l.

lit is to be noted that under the construction as above set forth, the hammer is thrown forward by the air acting between what may be termed two pairs of abutments, one movable and one fixed in each pair. So too, upon the return stroke the pressure is applied between a single pair of abutments. 'lt is likewise to be noted that the air is introduced through the drill-bar or rod into the center of the hammer, and that novalves, other than. as the pistonhannner performs that function, are necessary. vFunthermore, the air inits passage through the 'machine maintains the same general direction of travel, being introduced at one end and discharged at the other, preferably through the drillhead, and con-- soquently there is in effect no reversal of the air currents, which is a matter of importance in a tool of the character de scribed, in that it enables the drill to act with greater rapidity than where the air currents have to be reversed.

The term air 7 in the foregoing specili- `cation and in the claims is to be understood as the equivalent of any suitable gaseous medium susceptible of being compressed and pas nimeer a,

giving oid power due to expansion. So, too, the term pneumatic is used in a generic sense.

The introduction of the air in the qmanner set forth and the absence ci' valves enables me to produce a hammer of relatively small diameter and one which can be carried doun into the opening being drilled by a mere extension of the drill or feed bar. The latter feature is of marked advantage. in that it brings the hammer and operating parts thereof into close relationship to the drill-head.

While the device has been described as intended for use in conjunction with a drill, it will be readily appreciated that it may be employed for other purposes, any suitable tool being substituted `l'or the drill.

Having thus described my invention, what I claim is:

l. In a pneumatichammer, the combination of a shell or casing; a tube in direct communication with a source ot' fluid supply under pressure; a collar carried by the tube; means for securing the tube in place within one end of the shell; a iixed abutment carried by the tube intermediate its length and dividing the bore of the tube iuto two parts; a hammer-piston mounted on the tube and abutment and movable thereon, said piston being formed with two chambers, a rear relatively large one to function with the abutment, and a smaller outer one adapted to cooperate with the forward portion of the tube; and a series of ports arranged in said tube and piston to permit the air to pass into and from the chambers and to and :from the space between the rear of the piston and the collar, whereby the hammer-piston will be caused to reciprocate and deliver blows 2. ln a pneumatic hammer, the combination of a shell or casing; a tubular member secured in one end thereof a xed abutment carried by said member; a tubular extension projecting forwardly from said abutment, said member and said extension each having a port formed therein adjacent the abutment; a collar located adjacent the inner end of the tube and located between 'the tube and shell and forming a second abutment; a hammeopiston comprising a large and a 'small tubular section with a piston ring located at the junction of said sections, said ring being .larger than the larger tubular section and making a close t with the interior of the shell; a sleeve secured to the inner end of the piston andworking over the tubular member aforesaid; and ports formed .in the piston, adapted to cooperate with the ports aforesaid to cause the air to travel through the hammer to actuate the same.

ln testimony whereof l have signed my name to this specification in the presence of two subscribing witnesses.

JUSEPl-l D. MACDONALD. Witnessesz C. F. Guerin, C. C. LANTRY.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

Washingten, D, C. 

